CVE-2026-46303
Description
A flaw was found in the Linux kernel's isofs filesystem. This vulnerability allows a local attacker, by mounting a specially crafted ISO image, to read data beyond the boundaries of the intended ISO 9660 volume. This out-of-bounds read could lead to information disclosure, potentially exposing sensitive data from adjacent filesystems on the same block device.
Statement
This Moderate flaw in the Linux kernel's isofs filesystem allows a local attacker to disclose information. Exploitation requires local access and the ability to mount a specially crafted ISO image, which could occur via CAP_SYS_ADMIN or through desktop auto-mount features like udisks2. This could expose sensitive data from adjacent filesystems on the same block device.
Mitigation
To reduce exposure, restrict the ability of untrusted users to mount ISO images. If the `isofs` kernel module is not essential for system operation, it can be prevented from loading.
To blacklist the `isofs` module:
1. Create or edit `/etc/modprobe.d/blacklist-isofs.conf` and add:
blacklist isofs2. Regenerate the initramfs to apply the change:
install isofs /bin/true
bash3. A system reboot is required for this change to take full effect. This action may affect functionality requiring ISO 9660 filesystem mounts.
dracut -f -v
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 8.2 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | None | N/A | Low |
| Availability Impact | High | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
Understanding the Weakness (CWE)
Confidentiality
Technical Impact: Read Memory
An attacker could get secret values such as cryptographic keys, PII, memory addresses, or other information that could be used in additional attacks.
Confidentiality
Technical Impact: Bypass Protection Mechanism
Out-of-bounds memory could contain memory addresses or other information that can be used to bypass ASLR and other protection mechanisms in order to improve the reliability of exploiting a separate weakness for code execution.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker could cause a segmentation fault or crash by causing memory to be read outside of the bounds of the buffer. This is especially likely when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string.
Other
Technical Impact: Varies by Context
The read operation could produce other undefined or unexpected results.
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